Sundial erected in memory of John Gatenby Bolton, first director of the Parkes Telescope.

John Gatenby Bolton, (born June 5, 1922, Sheffield, England—died July 6, 1993, Buderim, Queensland, Australia), British-born Australian astronomer who was a pioneer in the field of radio astronomy and director (1961-71) of the Australian National Radio Astronomy Observatory, where the 64-m (210-ft) Parkes radio telescope played a crucial role in the U.S. Apollo space program.

Bolton studied mathematics and physics at Trinity College, Cambridge, and then served as a radar officer in the British Royal Navy (1942-46). He immigrated to Australia in 1946 and joined the staff of the Radiophysics Laboratory of the Commonwealth Council for Scientific and Industrial Research in Sydney. In 1948 Bolton’s team identified the first known radio galaxies, or "radio stars," external galaxies that can be traced by the strong signals they emit at radio wavelengths. He established the Owens Valley Radio Observatory during a six-year stint teaching physics and astronomy at the California Institute of Technology (1955-61), but in 1961 he returned to Australia to oversee construction of the Parkes dish.

In 1962-63, under Bolton’s direction, this radio telescope played a key role in the discovery of the prototype of a family of very distant and luminous objects called quasars. Bolton later used it to pinpoint more than 8,000 extragalactic radio sources, including hundreds of quasars. In 1969 the instrument became the ear of the world when it received the radio signals transmitted by Apollo 11 from the Moon. Bolton was made Commander of the Order of the British Empire in 1981.